This project involves studies on the biology of the parasitic protozoa Trichomonas vaginalis, Entameoba histolytica, and Giardia lamblia. In view of the retirement on June 30, 1982 of the principal investigator, the major emphasis for the nine month period has been on Trichomonas in collaboration with Dr. Michael R. Spence of The Johns Hopkins University School of Medicine involving metronidazole resistant trichomonad strains and therapy for drug resistant trichomoniasis. Current studies which will be continued at The Johns Hopkins University beginning July, 1982 will include the search for properties of trichomonads which may lead to more effective therapy than is currently avaialble for drug resistant trichomoniasis and a screening program to determine the magnitude of the problem of drug resistance in trichomonads.